Device for cleaning the cathode mercury in large rectifiers



Sept. 24, 1929. w. NEHLs 1,729,450

DEVICE FOR CLEANING THE CATHODE MERCURY IN LARG RECTIFIERS Filed May 26, 1928 INVENTOR Wa/er /Veh/s ATTORNEY Patented Sept. 24, 1929 UNITED STATES WALTER NEHLS, 0F BERLIN-SIEMENSESTADT, GER-MANY, ASSEGNGR "E0 'WESTNG- HOUSE ELECTRIC 8c MANFACTURXNG CVPANY, A COBPRATICN O1? PENNSYL- VANIA DEVICE FOR CLEANING THE CATHODE MERCURY IN LARGE RECTFERS Application filed May 26, 1928, Serial No,

My invention relates to mercury-arc rectifiers and it has particular relation to means for purifying the liquid mercury pool in large metal-tank rectiiiers.

In metal-tank mercury-vapor reetiliers, it frequently happens that many foreign bodies or particles are deposited in the containers during operation, resulting in the contamination of the liquid mercury pool which constitutes the cathode, by reason of the washing` down of the foreign bodies in the process of condensation of the mercury-vapor. By reason of their low specific weight, the foreign particles float on the surface of the cathode. For this reason, various means have previously been adopted to separate the foreign particles from the cathode mercury and to collect them in a portion of the cathode where the arc cannot play.

The object of my invention is to maintain the purity of the cathode mercury pool in such manner as to avoid the difficulties and shortcomings of previous devices for this purpose, and, in particular, to provide an external purifier or separating chamber which maybe removed from time to time, as may be necessary for the purpose of cleaning, Without disturbing the vacuum of the rectifier tank.

With the foregoing and other objects in view, my invention consists in the combinations and details of construction hereinafter more particularly described and claimed and illustrated in the accompanying drawing, wherein- Figure 1 is a vertical sectional view illus- 280,783, andY in Germany May 28, 19E?.

mercury is not returned directly to the eathode pool, and to this end, the cathode mercury is sub-divided by a tall insulating tube or cathode cup 10, into an active mercury-containing central space 11 and an annular inac` 5.5 tive space 12 surrounding the same. rifhe inactive space is closed at the top by a slanting annular cover 13, so that the used mercury which is condensed inside of the apparatus flows from the upper tank portion onto the slanting annuiar cover 13 over the inactive portion 1Q of the mercury and outside of the tali insulating cathode cup 10.

i/cccrdin g to my invention, l have also provided means for withdrawing the condensed mercury from above the inclined annular cover 13 and conducting it outside of the tank by means of a tube`15 which leads to a purifier or separating chamber 127 outside ofthe tank. .ln the pinifier, the mercury has a 7,0 chance to stand stiil and the floating particles of foreign matter rise to the surface, after which the mercury is withdrawn again, from a point at which there are no impurities, by means of a second tube 18 which enters the, 7:5 rectifier at a point below the annular cover member 13, thus discharging the mercury into the inactive spi ce 12, from which it 'flows underneath the cathode cup 10 into the active central cathode space 11.

The two tubes 15 and 18 which lead. to and from the purifier 17 are provided with detachable joints or couplings 19 and 20, respectively, whereby the purifier 1'? may be removed, from time to time, for emptying and cleaning. To this end, however, it is necessary to provide each tube with a vacuum valve 21, which may be closed prior to the opening of the couplings 19 and 20, so that the operation of the rectifier will not be disturbed dur-i 90 ing` the brief interval when the purifie' being cleaned.

The purifying of the mercury within the puriher or container 17 may be effected bv filter sieves or baffles or separators, or in any other known manner. The essential feature of my invention is that the purification is done outside of the rectifier tank, in a vessel which can be removed without disturbing the vacuum withinthe rectifier tank.

lt will be noted that the condensed mercury is freed of its impurities before it is led back to the cathode, beingtapped off, on its way to the cathode, and being caused to iiow, by its own gravity, through a purifier which is disposed outside of the rectiier.

In large rectifiers, it will be understood that a plurality of purifiers may be arranged around the cathode periphery, prefe ably in a symmetric arrangement. y

lt will be understood that suitable evacuating openings and pumps will be provided, together with the necessary valves and controlindicating apparatus, as is customary in rectiliers. As such features are only conven tional features of design, I have not deemed it necessary to illustrate the same.

TVhile l have illustrated my invention in a preferred form of embodiment, it is to be understood that lf am not altogether limited thereto, as many changes may be made by those skilled in the art, without departing from the essential features of my invention. I desire, therefore, that the appended claims shall be accorded the Widest construction commensurate with their language and the prior art.

I claim as my invention:

l. An evacuated mercury-vapor rectifier oil: the type in which the mercury vapor is condensed in an upper portion of the rectifier and returned to a mercury cathode pool in a lower portion thereof, characterized by hav ing a separate purifier disposed outside of the rectifier, partition means within the rectifier for trapping the condensed mercury as it flows toward the cathode pool, and pipes disposed above and below said partition means for leading the mercury to and from said purier as it flows, by gravity, into the cathode pool.

2. An evacuated mercury-vapor rectifier of the type in which the mercury vapor is condensed in an upper portion of the rectifier and returned to a mercury cathode pool in a lower portion thereof, characterized by hav ing` a separate purifier disposed outside of the rectiler, partition means within the rectifier' for trapping the condensed mercury as it flows toward the cathode pool, pipes disposed above and below said partition means for loading the mercury to and from said purifier as it flows, by gravity, into the cathode pool, said purifier being detachably connected to said pipes, and vacuum valves in said pipes.

An evacuated mercury-vapor rectifier comprising a mercury holder, a cathode mercury pool therein, a main tanlr thereabove including a plurality of anodes and a condensing space, an insulating cylindrical cathode cup dividing the mercury pool into a central active portion and an annular inactive portionv` au annular cover member over said inactive portion and spaced thereabove, and a purifying means for freeing the condensed WALTER NEHLS. 

